Scanning optical device, image forming apparatus, and method for assembling image forming lens

Abstract

To improve assemblability of an image forming lens to an optical box.SOLUTION: An optical box 101 has a contact part 135a at which one end of a second image forming lens 119b is located in a scanning direction, and a contact part 135b at which the other end of the second image forming lens 119b is located in the scanning direction. At a position that is adjacent in the scanning direction to the contact part 135a among two the contact part 135a and 135b and that is adjacent to a side of the contact part 135b, a slope 137 is provided, which extends in a direction directed from the contact part 135a toward the contact part 135b, and which is inclined to be reduced in height from the contact part 135a toward the contact part 135b.SELECTED DRAWING: Figure 5(a)

Description

[Technical Field]

[0001] The present invention relates to a scanning optical device used in an image forming apparatus such as a copying machine or a laser beam printer, an image forming apparatus equipped with this scanning optical device, and a method for assembling an imaging lens. [Background technology]

[0002] Patent Document 1 discloses a scanning optical device used in a color image forming apparatus using electrophotography. Specifically, the scanning optical device irradiates laser light onto photosensitive drums corresponding to four colors: yellow, magenta, cyan, and black. In addition, there has been a recent demand for cost reduction and miniaturization of image forming apparatuses. To address this demand, the scanning optical device described in Patent Document 1 houses multiple light sources and optical components corresponding to the four colors in a single optical box. Furthermore, laser light emitted from the multiple light sources is deflected by a single optical deflector and irradiated onto each photosensitive drum via a folding mirror. An fθ lens, one of the optical components used in the scanning optical device, is fixed in place with its position relative to the optical box restricted by the fθ lens abutting against a convex abutment provided on the optical box.

[0003] When assembling multiple optical components into a single optical box, the shapes of the optical components and the positions and orientations of the optical components relative to the optical box vary. Therefore, when performing automated assembly using machinery to shorten the assembly takt time, the machinery configuration becomes complex and large-scale in order to accommodate optical boxes with different specifications. Therefore, taking into account capital investment and labor costs, and from the perspective of return on investment for assembly, the process of assembling optical components into an optical box may be performed manually by a worker rather than by machinery.

[0004] When assembling optical components, workers must handle f-theta lenses, in particular, with care, as they have many optically functional parts. Specifically, when assembling an f-theta lens into an optical box, workers must grasp the edges of the f-theta lens rather than the center to prevent contamination (for example, fingerprints) from getting on the effective lens area of ​​the f-theta lens. Gripping both ends of the f-theta lens stabilizes the position and posture of the f-theta lens during assembly, but because both hands of the worker are occupied, only one f-theta lens can be assembled at a time.

[0005] On the other hand, for the purpose of improving productivity, if an operator grips only one end of an f-theta lens to assemble it into an optical box, it is possible to assemble two f-theta lenses at the same time, but this method poses the following problem: When an operator grips only one end of the f-theta lens and tries to abut the end of the f-theta lens that is not being gripped (hereinafter referred to as the non-gripped end) against a contact part of the optical box, the position and posture of the non-gripped end are unstable because the f-theta lens is long, making it difficult to achieve abutment. Therefore, to assemble the f-theta lens into the optical box while stabilizing the position and posture of the non-gripped end, a desirable assembly method is to slide the f-theta lens to the contact part of the optical box while the non-gripped end is abutting against a flat part such as the bottom of the optical box. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-164536 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when an assembly method is used in which only one end of the fθ lens is gripped and the non-gripped end is slid to the abutment portion of the optical box, the following problem occurs: Figure 11 is a cross-sectional view of the vicinity of the non-gripped end when this assembly method is used. Arrow Ds indicates the sliding direction of the fθ lens. As shown in Figure 11, the fθ lens 300 gets caught on a convex abutment 320 provided on the optical box 310 to regulate the position of the fθ lens 300, which reduces the ease of assembling the fθ lens to the optical box. Furthermore, the collision of the fθ lens can cause scratches and dents on the precision surfaces of each part, reducing the assembly accuracy, or the quality can be reduced due to assembly defects where the fθ lens is not installed in the correct position.

[0008] The present invention has been made under these circumstances, and has as its object to improve the ease of assembling an imaging lens into an optical box. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0010] (1) A scanning optical device comprising: a light source; a rotating polygon mirror that deflects and scans the light beam emitted from the light source; an imaging lens that is long in the scanning direction of the rotating polygon mirror and that images the light beam deflected and scanned by the rotating polygon mirror onto a surface to be scanned; and an optical box in which the rotating polygon mirror and the imaging lens are installed, wherein the optical box has a positioning portion that positions one end of the imaging lens in the scanning direction and a positioning portion that positions the other end of the imaging lens in the scanning direction, and at a position adjacent to one of the two positioning portions in the scanning direction and adjacent to the other positioning portion, there is provided an inclined surface that extends in a direction from one positioning portion to the other positioning portion, and the inclined surface is inclined so that its height decreases as it moves from one positioning portion to the other positioning portion. [Effects of the Invention]

[0011] According to the present invention, the ease of assembling the imaging lens into the optical box can be improved. [Brief explanation of the drawings]

[0012] [Figure 1]Cross-sectional view of an image forming apparatus [Figure 2] 1 is a perspective view of a scanning optical device according to a first embodiment of the present invention; [Figure 3] 1 is a cross-sectional view of a scanning optical device according to a first embodiment of the present invention; [Figure 4] FIG. 1 is a perspective view of a second imaging lens according to a first embodiment; [Figure 5(a)] FIG. 1 is a perspective view of a portion of an optical box according to a first embodiment; [Figure 5(b)] FIG. 1 is a perspective view of a portion of an optical box according to a first embodiment; [Figure 5(c)] FIG. 1 is a perspective view of a portion of an optical box according to a first embodiment; [Figure 6] 1 is a cross-sectional view of the contact portion of the optical box according to the first embodiment; [Figure 7(a)] FIG. 10 is an explanatory diagram showing the assembly process of the second imaging lens of the first embodiment to the optical box. [Figure 7(b)] FIG. 10 is an explanatory diagram showing the assembly process of the second imaging lens of the first embodiment to the optical box. [Figure 7(c)] FIG. 10 is an explanatory diagram showing the assembly process of the second imaging lens of the first embodiment to the optical box. [Figure 7(d)] FIG. 10 is an explanatory diagram showing the assembly process of the second imaging lens of the first embodiment to the optical box. [Figure 7(e)] FIG. 10 is an explanatory diagram showing the assembly process of the second imaging lens of the first embodiment to the optical box. [Figure 8] FIG. 10 is an explanatory diagram showing that the assembly efficiency of the second imaging lens of the first embodiment is improved. [Figure 9] FIG. 10 is a perspective view of a second imaging lens according to a second embodiment; [Figure 10] FIG. 10 is an explanatory diagram showing an improvement in assembly efficiency of the second imaging lens of the second embodiment. [Figure 11] A diagram showing an example of the assembly process of an fθ lens into an optical box. [Figure 12] 1 is a cross-sectional view showing a first modification of the first embodiment; [Figure 13] 1 is a cross-sectional view showing a second modification of the first embodiment; [Figure 14] FIG. 10 is a perspective view showing a second modification of the first embodiment; DETAILED DESCRIPTION OF THE INVENTION [Example]

[0013] A first embodiment of an image forming apparatus 1 according to the present invention will be described with reference to FIGS.

[0014] (Image forming device overview) FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 according to a first embodiment. The image forming apparatus 1 according to the first embodiment is a color image forming apparatus that forms a full-color image by superimposing four colors: yellow, cyan, magenta, and black. Next, the image forming process will be described. The process cartridges PY, PM, PC, and PK, each corresponding to a different color, are equipped with photosensitive drums 11a, 11b, 11c, and 11d as image carriers (scanned surfaces), charging rollers 12a, 12b, 12c, and 12d as charging devices, and developing rollers 13a, 13b, 13c, and 13d as developing devices. The process cartridges PY, PM, PC, and PK may also be collectively referred to as process cartridges P. Regarding the components of each process cartridge P, a represents yellow, b represents magenta, c represents cyan, and d represents black. Hereinafter, the components a to d within the process cartridge P will also be omitted unless a specific color is described. The same applies to a primary transfer roller 22, which will be described later.

[0015] The photosensitive drum 11, which has been pre-charged by the charging roller 12, is irradiated with laser beams L1, L2, L3, and L4 emitted from the scanning optical device 2, which serves as an exposure device, to form an electrostatic latent image on its surface. The electrostatic latent image is converted into a toner image by the developing roller 13, which serves as a developing means, and the toner image on the photosensitive drum 11 is transferred onto the intermediate transfer belt 21 by the primary transfer roller 22 (primary transfer). Meanwhile, a recording sheet S, which serves as a recording material and is placed in a paper cassette 31 located below the intermediate transfer belt 21, is picked up by a pickup roller 32 in synchronization with the image formation process. The conveyed recording sheet S is then transferred with the four-color toner image on the intermediate transfer belt 21 by the secondary transfer roller 33, which serves as a transfer means (secondary transfer). Finally, the recording sheet S passes through a fixing device 34, where the unfixed toner image is fixed, and the recording sheet S is discharged by discharge rollers 35 and 36 to a discharge tray 37 outside the image forming apparatus 1.

[0016] (Scanning optical device overview) Next, the scanning optical device 2 of Example 1 will be described with reference to Figures 2 and 3. Figure 2 is a schematic perspective view showing the configuration of the scanning optical device 2, and shows a state in which the cover 102 (see Figure 3) is removed in order to explain the inside of the scanning optical device 2. In the coordinate system of Example 1, the direction of the rotation axis CZ of the rotating polygon mirror 103 is defined as the Z direction, the scanning direction of the laser beams L1, L2, L3, and L4 deflected and scanned by the rotating polygon mirror 103 is defined as the Y direction, and the direction perpendicular to the Y direction and the Z direction is defined as the X direction.

[0017] Four semiconductor lasers 111 serving as light sources are attached to the side of an optical box 101 of the scanning optical device 2. Laser beams L1, L2, L3, and L4 emitted from the four semiconductor lasers 111 are converted into substantially parallel or convergent beams in the X direction and convergent beams in the Z direction by an anamorphic lens 113, which is an integrally formed combination of a collimator lens and a cylindrical lens. Thereafter, the beam widths of the laser beams L1, L2, L3, and L4 are limited by a sub-scanning aperture stop and a main-scanning aperture stop (not shown), and the beams are imaged linearly with a constant width in the X direction on the deflecting reflecting surface of the rotating polygon mirror 103.

[0018] A scanner motor 104 that rotates the rotating polygon mirror 103 around a rotation axis CZ is attached to the optical box 101 with screws (not shown). A beam detector (hereinafter referred to as BD) 125 is mounted on a control board 124. In the first embodiment, the laser beam L4 is reflected by the rotating polygon mirror 103, deflected and scanned, and enters the BD 125. At this time, the writing of images of each color is controlled based on a signal output from the BD 125 (hereinafter referred to as a BD signal).

[0019] Next, referring to FIG. 3 , the scanning optical system of the laser beams L1, L2, L3, and L4 in the first embodiment after reflection by the rotating polygon mirror 103 will be described. FIG. 3 is a cross-sectional view of the scanning optical system in the sub-scanning direction, showing the optical paths of the laser beams L1, L2, L3, and L4 deflected and scanned by the rotating polygon mirror 103 until they reach the photosensitive drums 11a, 11b, 11c, and 11d. The first embodiment is an optical system called an oblique incidence scanning optical system, which causes the laser beams L1, L2, L3, and L4 to be obliquely incident on the deflective reflection surface of the rotating polygon mirror 103 in the Z direction and then split into upper and lower optical paths after reflection by the rotating polygon mirror 103. Because it is an oblique incidence scanning optical system, the laser beams L1 and L3 are reflected downward by the rotating polygon mirror 103, and the laser beams L2 and L4 are reflected upward by the rotating polygon mirror 103 in the Z direction. The laser beams L1, L2, L3, and L4 then enter a first imaging lens 116.

[0020] Next, the laser beams L2 and L3 are reflected by the first reflecting mirror 117. After that, the laser beams L2 and L3 pass through the second imaging lens 119a and are reflected again by the second reflecting mirror 118 before reaching the photosensitive drums 11b and 11c. The laser beams L1 and L4 pass through the second imaging lens 119b and are reflected by the third reflecting mirror 120 before reaching the photosensitive drums 11a and 11d. With this configuration, the first imaging lens 116 is a common lens for the laser beams L1, L2, L3, and L4, the second imaging lens 119a is a common lens for the laser beams L2 and L3, and the second imaging lens 119b is a common lens for the laser beams L1 and L4. Each imaging lens is fixed to the optical box 101 with a UV adhesive, and each reflecting mirror is fixed with a biasing member (not shown). A cover 102 for preventing dust particles from entering the scanning optical device 2 is attached to the optical box 101 with screws (not shown).

[0021] Hereinafter, the shapes of the optical box 101 around the second imaging lenses 119a, 119b and the multiple abutment portions (positioning portions) that regulate (position) the positions of the second imaging lenses 119a, 119b will be described. Note that the shapes of the second imaging lenses 119a, 119b and the shape of the optical box 101 around the abutment portions for each lens have similar configurations. Therefore, in Example 1, the second imaging lens 119b through which the laser light beam L1 passes, the corresponding abutment portion of the optical box 101, and the configuration around it will be described as a representative example.

[0022] (External dimensions of the second imaging lens) Next, the shape of the second imaging lens 119b in Example 1 will be described with reference to Fig. 4. The second imaging lens 119b has two positioned portions 130 and 132 on each end in the Y direction (in other words, the longitudinal direction). A shape similar to the positioned portion 132 is also provided on the opposing surface (the surface on the -Z direction side in Fig. 4). With this configuration, by inverting the second imaging lens 119b upside down, it can be used as a common lens for the laser beam L1 and the laser beam L4, as described above.

[0023] More specifically, the second imaging lens 119b has a lens portion 119b1, surfaces 119b2 and 119b3, and end surfaces 119b4 and 119b5. As described above, the lens portion 119b1 is a portion through which the laser beam L1 or the laser beam L2 passes. The lens portion 119b1 has a surface 119b1a onto which the laser beam L1 or the laser beam L2 is incident, and a surface 119b1b (see FIG. 7(a)) from which the laser beam L1 or the laser beam L2 emerges.

[0024] The surface 119b2 is a surface orthogonal to the surface 119b1a of the lens portion 119b1 and is a surface provided along the longitudinal direction of the second imaging lens 119b. The above-mentioned positioned portions 132 (132a, 132b) are provided at both ends of the surface 119b2 in the longitudinal direction of the second imaging lens 119b. Specifically, the positioned portion 132a is provided at one end in the longitudinal direction of the second imaging lens 119b, and the positioned portion 132b is provided at the other end. The surface 119b3 is the surface opposite to the surface 119b2, and positioned portions (not shown) are provided at positions on the surface 119b3 corresponding to the positioning portion-positioned portions 132 (132a, 132b) provided on the surface 119b2. Note that although the positioned portion 132 has a circular shape in FIG. 4, it may have another shape, such as an elliptical shape. The end surface 119b4 is a surface orthogonal to the surfaces 119b2 and 119b3, is provided on one end side of the lens portion 119b1, and is provided with the positioned portion 130a (130). The end surface 119b5 is a surface orthogonal to the surfaces 119b2 and 119b3, is provided on the other end side of the lens portion 119b1, and is provided with the positioned portion 130b (130). In FIG. 4, the positioned portion 130 has an elongated elliptical shape extending in a direction orthogonal to the surfaces 119b2 and 119b3, i.e., in the Z direction. Note that the positioned portion 130 is not limited to an elliptical shape and may have other shapes, such as a rectangular shape. Alternatively, it may have a plurality of circular shapes lined up in the Z direction, for example.

[0025] A positioned portion 131 is provided at one end (one end) of the second imaging lens 119b. A corner C1 serving as a first corner is a corner formed by the surface 119b2 and the positioned portion 131. A corner C2 serving as a second corner is a corner formed by the surface 119b3 and the positioned portion 131. A convex portion 140 is provided at the other end (the other end) of the second imaging lens 119b. The convex portion 140 protrudes from the end surface 119b5 in the longitudinal direction in a direction away from the lens portion 119b1.

[0026] (Shape of the optical box around the contact part that regulates the position of the second imaging lens) Next, the shape of the optical box 101 including the "second imaging lens 119b arranged on the laser optical path of the laser beam L1," the contact portion with which it contacts, and the surrounding area will be described using Figure 5. Figure 5(a) is a perspective view of the contact portion and the surrounding area of ​​the optical box 101. Figure 5(b) is a detailed view of the vicinity of the circular frame portion A in Figure 5(a). Figure 5(c) is a detailed view of the vicinity of the circular frame portion B in Figure 5(a). The circular frame portion A is an area corresponding to one end of the second imaging lens 119b, and the circular frame portion B is an area corresponding to the other end of the imaging lens 119b.

[0027] Optical box 101 is provided with contact portions against which imaging lens 119b abuts, and the contact portions are provided at positions corresponding to one end of imaging lens 119b and the other end of imaging lens 119b in the scanning direction. Specifically, optical box 101 is provided with contact portions (positioning portions for positioning second imaging lens 119b) 133, 134, 135a, and 135b against which second imaging lens 119b abuts, and adhesive portion 136 for fixing imaging lens 119b. Contact portions 133, 135a, and 135b protrude beyond the periphery of each contact portion to facilitate dimensional accuracy during molding, and more specifically, have a convex shape relative to the periphery. When the second imaging lens 119b is assembled to the optical box 101, the abutting portion 133a as the second abutting portion comes into contact with the positioned portion 130a as the second positioned portion, and the abutting portion 133b comes into contact with the positioned portion 130b (see also FIG. 4). The abutting portion 135a as the first abutting portion comes into contact with the positioned portion 132a as the first positioned portion, the abutting portion 135b comes into contact with the positioned portion 132b, and the abutting portion 134 as the third abutting portion comes into contact with the positioned portion 131 as the third positioned portion (see also FIG. 4). In this way, one end of the second imaging lens 119b in FIG. 4 is assembled near the circular frame portion A in FIG. 5(a), and the other end of the second imaging lens 119b in FIG. 4 is assembled near the circular frame portion B. The contact portions 135a and 133a correspond to one of the contact portions, and the contact portions 135b and 133b correspond to the other of the contact portions. With this configuration, the second imaging lens 119b is positioned relative to the optical box 101 in the X, Y, and Z directions.

[0028] The contact portion 133 is a second positioning portion that determines the position of the second imaging lens 119b in the X-axis direction. The contact portion 134 is a third positioning portion that determines the position of the second imaging lens 119b in the Y-axis direction. The contact portion 135a is a first positioning portion that determines the position of the second imaging lens 119b in the Z-axis direction. The contact portion 135b is the other first positioning portion that determines the position of the second imaging lens 119b in the Z-axis direction. The surfaces of these contact portions (positioning portions) that the second imaging lens 119b abuts are flat surfaces (positioning surfaces).

[0029] Furthermore, between the contact portion 135a on one end side and the bottom surface 101a of the optical box 101, there is provided a slope 137 as an inclined surface that slopes toward the other contact portion 135b. In other words, the height of the slope 137 from the bottom surface 101a of the optical box 101 gradually decreases from the height of the contact portion 135a toward the contact portion 135b on the other end side. It is desirable that the ridge line connecting the contact portion 135a and the slope 137 has a smooth shape, such as a blend shape (curved shape). Note that the contact portions 135a and 133a can be considered as contact portions on the end side where the inclined surface is provided, and the contact portions 135b and 133b can be considered as end sides where the inclined surface is not provided.

[0030] In the first embodiment, the contact portion 135a has a rectangular convex shape, but this is not limiting and may have, for example, a cylindrical convex shape. In the case of a cylindrical convex shape, the inclined surfaces may be surfaces extending radially from the contact portion 135a. Note that, when optical components are assembled to the optical box 101, the bottom surface 101a of the optical box 101 is generally oriented downward, with the Z direction being the direction of gravity. Note that, in the scanning optical device 2 of this embodiment, the bottom surface 101a is oriented in the +Z direction, as shown in FIG. 3. Furthermore, when viewed in the Z direction, the bottom surface 101a is a surface that overlaps most of the area of ​​the lens portion 119b1 of the second imaging lens 119b in the longitudinal direction.

[0031] (Regarding slopes) Next, the area next to the contact portion where the inclined surface 137 is provided will be described with reference to FIG. 6. FIG. 6 is a partial cross-sectional view (seen in the Y direction) of the vicinity of the contact portion 135a of the second imaging lens 119b, showing a cross-section on a virtual plane perpendicular to the scanning direction. In the following description, the direction in which the second imaging lens 119b contacts the contact portion 135a is referred to as a contact direction T1 as a first contact direction, and the direction in which the second imaging lens 119b contacts the contact portion 133a is referred to as a contact direction T2 as a second contact direction. The second contact direction is a direction intersecting with the first contact direction. Note that a third contact direction T3 (see FIG. 5(b)), which is the direction in which the second imaging lens 119b contacts the contact portion 134, is a direction perpendicular to the contact direction T1 and the contact direction T2 and is parallel to the scanning direction (more specifically, the +Y direction).

[0032] In the first embodiment, the angle between the rotation axis CZ of the rotating polygon mirror 103 and the contact direction T2 of the second imaging lens 119b at the contact portion 133a is defined as θ2 as a second angle. The angle between the rotation axis CZ and the contact direction T1 of the second imaging lens 119b at the contact portion 135a is defined as θ1 as a first angle. In the first embodiment, θ2 is 90° and θ1 is 0°. In this case, the contact direction T2 is perpendicular to the contact direction T1. The inclined surface 137 is provided next to the contact portion that forms a smaller angle with the rotation axis CZ of the rotating polygon mirror 103. In the first embodiment, since θ1<θ2, the inclined surface 137 is provided at the contact portion 135a. Furthermore, since θ1<θ2, the inclination of the contact direction T1 is closer to the direction of gravity than the contact direction T2. In addition, the inclined surface 137 is disposed on the side farther from the contact portion 134 than the contact portion 135a in the longitudinal direction of the lens.

[0033] 12 to 14 show modified examples of the first embodiment in which the relationship between θ1 and θ2 is different from that shown in FIG. 6. FIG. 12 shows modified example 1, in which the contact surfaces 133p and 135ap are inclined by 30° around the Y axis compared to the first embodiment (FIG. 6). In FIG. 12, θ1 is 30° and θ2 is 60°. Therefore, as in FIG. 6, the relationship θ1<θ2 is satisfied, and thus the inclined surface 137p is provided next to the contact portion 135ap. Furthermore, as in FIG. 6, the relationship θ1<θ2 is satisfied, and thus the contact direction T1 is inclined closer to the weight direction than the contact direction T2.

[0034] FIG. 13 shows Modification 2, in which the contact surfaces 133q and 135aq are inclined by 60° around the Y axis compared to Example 1 (FIG. 6). In FIG. 13, θ1 is 60° and θ2 is 30°. Therefore, since θ1 > θ2, the inclined surface 137q is provided adjacent to the contact portion 133q (more precisely, the adhesive portion 136q) rather than adjacent to the contact portion 135aq. FIG. 14 is a perspective view of Modification 2. Furthermore, since θ1 > θ2, the inclination of the contact direction T2 is closer to the weight direction than the inclination of the contact direction T1. In FIG. 14, the contact portion 133q and the adhesive portion 136q are flat. This allows the imaging lens 119b, which moves while in contact with the inclined surface 137q, to ​​move smoothly to the contact portion 133q via the adhesive portion 136q during device assembly. In the second modification, no inclined surface is provided next to the contact portion 135aq.

[0035] As described above, the position of the inclined surface 137 can be determined depending on the magnitude relationship between θ1 and θ2. In this embodiment, the direction of the rotation axis CZ is parallel to the direction of gravity.

[0036] (Second imaging lens assembly method) Next, the process of assembling the second imaging lens 119b to the optical box 101 in Example 1 will be described with reference to Figs. 7(a) to 7(e). Fig. 7(a) is a schematic diagram at the start of the assembling process, and Fig. 7(b) is a detailed diagram of the circular frame portion C shown in Fig. 7(a) at the start of the assembling process. Figs. 7(c) to 7(e) show detailed diagrams at various timings in the assembling process. Fig. 7(a) and others are cross-sectional views taken along line DD shown in Fig. 5(a).

[0037] In the first embodiment, when assembling the second imaging lens 119b to the optical box 101, an operator holds the end E1 of the second imaging lens 119b (FIG. 7(a)), and brings the corner C1 on the positioned portion 131 side into contact with the bottom surface 101a of the optical box 101 (FIG. 7(b)). The end E1 is the other end of the second imaging lens 119b described in FIG. 4, the end where the convex portion 140 is provided, and the end opposite in the Z-axis direction from the side where the corner C1 is provided.

[0038] Thereafter, the worker slides the second imaging lens 119b in the direction S indicated by the arrow in FIG. 7(a) from a state in which the second imaging lens 119b is in contact with the bottom surface 101a of the optical box 101. As a result, the second imaging lens 119b climbs the inclined surface 137 provided in front of the contact portion 135a in the S direction (FIG. 7(c)). Then, the worker continues to move the second imaging lens 119b in the S direction, thereby causing the positioned portion 131 to abut against the abutment portion 134 (FIG. 7(d)). More specifically, the corner C1 of the second imaging lens 119b moves from the bottom surface 101a of the optical box 101 to the inclined surface 137 and climbs up the inclined surface 137, and the corner C2 abuts against the abutment portion 134. This restricts (positions) movement in the Y direction (longitudinal direction).

[0039] With the corner C2 of the positioned portion 131 in contact with the contact portion 134, the worker lowers the end portion E1 in the Z direction; in other words, moves the end portion E1 closer to the bottom surface 101a of the optical box 101. Then, the second imaging lens 119b climbs up the slope 137 and is temporarily placed on the optical box 101 with the surface 119b3 in contact with the contact portion 135a (FIG. 7(e)). In the temporarily placed state, the contact portion 134 of the optical box 101 and the positioned portion 131 of the second imaging lens 119b are in contact. At the other end of the second imaging lens 119b, the contact portion 135b and the positioned portion 132 are in contact. In addition, in the temporary placement state, the convex portion 140 of the second imaging lens 119b is housed in the concave portion 139 of the optical box 101 (see FIGS. 5(a) and 5(c)).

[0040] By temporarily placing the second imaging lens 119b at a predetermined position on the optical box 101, the orientation of the second imaging lens 119b relative to the optical box 101 is stabilized, allowing subsequent assembly processes such as bonding to the optical box 101 to proceed smoothly. With the second imaging lens 119b temporarily placed, the worker applies adhesive to the bonding portions 136a and 136b. Since the second imaging lens 119b has been positioned in the Y and Z directions, the worker moves the second imaging lens 119b in the X direction, more specifically, in the direction in which the bonding portions 136a and 136b are provided. As a result, at one end of the lens in the longitudinal direction, the positioned portion 130a of the second imaging lens 119b abuts against the abutting portion 133a of the optical box 101, and the end surface 119b4 of the second imaging lens 119b is bonded to the bonding portion 136a of the optical box 101. At the other end in the lens longitudinal direction, a positioned portion 130b of the second imaging lens 119b abuts against an abutting portion 133b of the optical box 101, and an end surface 119b5 of the second imaging lens 119b is adhered to an adhesive portion 136b of the optical box 101. The adhesive may be applied manually by an operator, or by other means such as a dispenser, a sticker, or a print.

[0041] As described above, in the first embodiment, when the second imaging lens 119b is assembled to the optical box 101, the second imaging lens 119b abuts against the optical box 101 in the direction of its own weight. Therefore, the position of the second imaging lens 119b in the Z direction relative to the optical box 101 is determined by its own weight without the worker applying any force. Therefore, in the assembly method in which the worker grasps the end E1 of the second imaging lens 119b and slides the second imaging lens 119b from a state in which the second imaging lens 119b abuts against the optical box 101 to assemble it to the optical box 101, the following can be achieved. That is, the worker can smoothly assemble the second imaging lens 119b to a predetermined position by simply applying a sliding force in the Y direction to the second imaging lens 119b. As a result, a scanning optical device 2 can be realized in which the second imaging lens 119b can be assembled to the optical box 101 with improved ease. The same effect can be obtained when assembling the second imaging lens 119a.

[0042] Furthermore, with the above-described configuration, the second imaging lenses 119a and 119b can be assembled to the optical box 101 while one end (end E1) of each of the second imaging lenses 119a and 119b is being held. That is, the second imaging lens 119b for the laser beam L1 can be held with one hand, and the second imaging lens 119b for the laser beam L4 can be held with the other hand. Therefore, as shown in FIG. 8, the worker can assemble the two second imaging lenses 119b to the optical box 101 at the same time. This makes it possible to realize a scanning optical device 2 with improved assembly efficiency for the second imaging lenses 119a and 119b.

[0043] Note that an inclined surface may also be provided on the other end side in the scanning direction. That is, an inclined surface whose height decreases from the contact portion 135b toward the contact portion 135a may be provided next to the contact portion 135b. Furthermore, as shown in FIGS. 13 and 14, when θ2<θ1, an inclined surface whose height decreases from the contact portion 133q toward the contact portion 133b corresponding to the opposite end in the lens longitudinal direction may be provided on the contact portion 133q. Furthermore, when θ2<θ1, an inclined surface whose height decreases from the contact portion 133b toward the contact portion 133a may be provided next to the contact portion 133b.

[0044] As described above, according to the first embodiment, it is possible to improve the ease of assembling the imaging lens into the optical box. [Example]

[0045] FIG. 9 is a schematic diagram of a second imaging lens 219b according to a second embodiment. The same reference numerals are used to designate the same functions and shapes as in the first embodiment, and their descriptions are omitted. In the second embodiment, the optical box does not include the inclined surface 137. Instead, the second imaging lens 219b includes an inclined surface 238. The second imaging lens 219b of the second embodiment includes an inclined surface 238 adjacent to the third positioned portion 231 in the Z-axis direction. Specifically, the corner C1 of the first embodiment corresponds to the inclined surface 238b, and the corner C2 corresponds to the inclined surface 238a. By providing the inclined surfaces 238 at both ends of the positioned portion 231 in the Z-direction, the second imaging lens 219b can be inverted and used as a common lens for both the laser beam L1 and the laser beam L4. The corner formed by the positioned portion 231 and the inclined surface 238b is designated as corner C3. The corner C3 can also be said to be a corner on the opposite side in the Z direction to the corner between the inclined surface 238a and the positioned portion 231.

[0046] Similarly, in the second embodiment, the optical box 101 is provided with a contact portion 235a and contact portions 133a and 134 as first contact portions (first positioning portions). Therefore, by replacing the contact portion 135a in FIG. 6 with the contact portion 235a in the second embodiment, the angle between the rotation axis CZ and the contact direction T1 can be set to θ1, and the angle between the rotation axis CZ and the contact direction T2 can be set to θ2. Note that, in the second embodiment, θ1 is set to 0 degrees and θ2 is set to 90 degrees. Thus, in the second embodiment, the inclined surface 238a can be said to be an inclined surface provided between the positioned portion 231 and the positioned portion 132a at θ1, which is the smaller angle between θ1 and θ2.

[0047] 10 shows a detailed view of the process of assembling the second imaging lens 219b to the optical box 101. The contact portion 235a of the optical box 101 in the second embodiment has a rectangular convex shape, and there is no inclined surface next to the contact portion 235a, unlike the inclined surface 137 in the first embodiment. In this configuration, the second imaging lens 219b is assembled to the optical box 101 by the assembly method described above. In this case, as shown in FIG. 10, the inclined surface 238a of the second imaging lens 119b remains in smooth contact with the contact portion 235a while the lens slides in the S direction, allowing the worker to assemble the second imaging lens 219b in a predetermined position with good workability. After the corner C3 of the second imaging lens 119b comes into contact with the contact portion 134 by sliding in the S direction, the worker brings the end E1 that he is holding close to the bottom surface 101a of the optical box 101, and temporarily places the second imaging lens 119b on the optical box 101. At this time, the positioned portion 132 of the second imaging lens 119b comes into contact with the contact portion 235a of the optical box 101. The rest is the same as in Example 1, and therefore a description thereof will be omitted.

[0048] As a result, it is possible to realize a scanning optical device 2 in which the second imaging lens 219b can be easily attached to the optical box 101. Furthermore, in the second embodiment, the inclined surfaces 238a and 238b are flat, but are not limited to this shape. For example, if the inclined surfaces 238a and 238b are surfaces without irregularities, such as arc-shaped surfaces, the same effect as the above-described configuration can be obtained.

[0049] As described above, according to the second embodiment, it is possible to improve the ease of assembling the imaging lens into the optical box. [Explanation of symbols]

[0050] 2. Scanning optical device 101 Optical box 119a, 119b Second imaging lens 135a, 135b Contact part 137 Slope

Claims

1. A light source and a rotating polygon mirror that deflects and scans the light beam emitted from the light source; an imaging lens that is elongated in the scanning direction of the rotary polygon mirror and that forms an image of the light beam deflected and scanned by the rotary polygon mirror on a surface to be scanned; an optical box in which the rotary polygon mirror and the imaging lens are installed; Equipped with the optical box has a positioning portion that positions one end of the imaging lens in the scanning direction, and a positioning portion that positions the other end of the imaging lens in the scanning direction, a position adjacent to one of the two positioning units in the scanning direction and adjacent to the other positioning unit, the position having an inclined surface extending in a direction from the one positioning unit to the other positioning unit, the inclined surface being inclined so that its height decreases as it moves from the one positioning unit to the other positioning unit; A scanning optical device characterized by:

2. When the positioning portion is defined as a first positioning portion and the direction in which the imaging lens abuts on the first positioning portion is defined as a first abutment direction, the optical box has a second positioning portion that positions the imaging lens in a second abutment direction that intersects both the first abutment direction and the scanning direction, When an angle formed between a rotation axis of the rotary polygon mirror and the first abutment direction is defined as a first angle and an angle formed between the rotation axis and the second abutment direction is defined as a second angle, the inclined surface is provided adjacent to the positioning part that forms the smaller angle of the first angle and the second angle.

2. The scanning optical device according to claim 1.

3. When the first angle is 0 degrees and the second angle is 90 degrees, the optical box has a third positioning portion that positions the imaging lens in the scanning direction, the inclined surface is disposed at a position adjacent to the first positioning unit in the scanning direction and on a side farther from the third positioning unit.

3. The scanning optical device according to claim 2.

4. A light source and a rotating polygon mirror that deflects and scans the light beam emitted from the light source; an imaging lens that is elongated in the scanning direction of the rotary polygon mirror and that forms an image of the light beam deflected and scanned by the rotary polygon mirror on a surface to be scanned; an optical box in which the rotary polygon mirror and the imaging lens are installed; Equipped with The imaging lens is a first positioned portion provided in a direction perpendicular to the scanning direction and abutting against the optical box in a first abutment direction; a second positioned portion that is provided in a direction intersecting the first positioned portion in an imaginary plane perpendicular to the scanning direction and that abuts against the optical box in a second abutment direction intersecting the first abutment direction; a third positioned portion that abuts against the optical box in the scanning direction; an inclined surface provided between the positioned portion that forms a smaller angle of the first angle and the second angle, when the angle formed by the rotation axis of the rotary polygon mirror and the first abutment direction is a first angle and the angle formed by the rotation axis and the second abutment direction is a second angle, and the third positioned portion; having A scanning optical device characterized by:

5. The optical box has a first positioning portion that protrudes from the surrounding area and abuts against the first positioned portion, and a second positioning portion that protrudes from the surrounding area and abuts against the second positioned portion.

5. The scanning optical device according to claim 4.

6. an image carrier that carries an electrostatic latent image; the scanning optical device according to claim 1 , which forms the electrostatic latent image; a developing means for developing the electrostatic latent image to form a toner image; a transfer means for transferring the toner image onto a recording material; Equipped with An image forming apparatus characterized by:

7. A method for assembling an imaging lens of a scanning optical device including: a light source; a rotary polygon mirror that deflects and scans a light beam emitted from the light source; an imaging lens that is elongated in a scanning direction of the rotary polygon mirror and that images the light beam deflected and scanned by the rotary polygon mirror onto a surface to be scanned; and an optical box that has a bottom surface and on which the rotary polygon mirror and the imaging lens are installed, the optical box has, at one end in the scanning direction, a first positioning portion that protrudes from its surroundings and positions the imaging lens in a first abutment direction that is perpendicular to the scanning direction, a second positioning portion that positions the imaging lens in a second abutment direction that is perpendicular to the scanning direction and intersects with the first abutment direction, a third positioning portion that positions the imaging lens in the scanning direction, and an inclined surface that extends from the first positioning portion toward the other end in the scanning direction so as to become lower in height, the imaging lens includes a first positioned portion that abuts against the first positioning portion, a second positioned portion that abuts against the second positioning portion, a third positioned portion that abuts against the third positioning portion, and a first corner portion between the first positioned portion and the third positioned portion; a second corner portion between the first positioned portion and the third positioned portion, the second corner portion facing the first corner portion, a step of abutting the first corner portion against the bottom surface and sliding the imaging lens toward the first positioning portion to move the first corner portion up along the inclined surface; a step of bringing the second corner portion into contact with the third positioning portion, and bringing the third positioned portion into contact with the third positioning portion while moving the other end of the imaging lens in the scanning direction toward the bottom surface; a step of temporarily placing the imaging lens on the bottom surface by bringing the first positioned portion and the first positioning portion into contact with each other; a step of bringing the second positioned portion and the second positioning portion into contact with each other; Equipped with A method for assembling an imaging lens, comprising:

8. A method for assembling an imaging lens of a scanning optical device including: a light source; a rotary polygon mirror that deflects and scans a light beam emitted from the light source; an imaging lens that is elongated in a scanning direction of the rotary polygon mirror and that images the light beam deflected and scanned by the rotary polygon mirror onto a surface to be scanned; and an optical box that has a bottom surface and on which the rotary polygon mirror and the imaging lens are installed, the imaging lens has: a first positioned portion that is provided in a direction perpendicular to the scanning direction and that abuts against the optical box in a first abutment direction; a second positioned portion that is provided in a direction intersecting the first positioned portion in an imaginary plane that is perpendicular to the scanning direction and that abuts against the optical box in a second abutment direction that intersects with the first abutment direction; a third positioned portion that abuts against the optical box in the scanning direction; and an inclined surface that is provided between the positioned portion that forms the smaller of the first angle and the second angle, and the third positioned portion, the optical box has a first positioning portion that protrudes from the surrounding area and abuts against the first positioned portion, a second positioning portion that protrudes from the surrounding area and abuts against the second positioned portion, and a third positioning portion that abuts against the third positioned portion, a step of abutting one end of the imaging lens on the bottom surface and sliding it toward the first positioning portion to move the imaging lens in a state where the first positioning portion and the inclined surface are in contact with each other; a step of abutting the third positioning portion with a corner opposite to the corner between the inclined surface abutting the bottom surface and the third positioned portion, and abutting the third positioned portion with the third positioning portion while moving the other end of the imaging lens in the scanning direction toward the bottom surface; a step of temporarily placing the imaging lens on the bottom surface by bringing the first positioned portion and the first positioning portion into contact with each other; a step of bringing the second positioned portion and the second positioning portion into contact with each other; Equipped with A method for assembling an imaging lens, comprising:

Images